Bad News About Coral Bleaching

As a diver and someone who wants to preserve the oceans for future generations I am extremely concerned about the current trends in coral bleaching. Coral bleaching is occurring in many areas due to increasing water temperatures from global warming. The hardest hit area this summer has been the Great Barrier Reef. According to the Guardian almost a quarter of the coral has been killed this year and 93 percent of the 3000 reefs in the Great Barrier have been hit by some level of bleaching (Slezak 2016). While bleaching is not new, the level and duration of the bleaching is becoming worse with every passing year. Before it would only happen during hot and calm conditions in localized areas but now we are seeing large regions experiencing this phenomenon especially in times of an El Niño.

Healthy Brain Coral

Coral is an animal that symbiotically uses algae as a source of energy. The coral captures algae and the algae converts the sun’s rays into energy through photosynthesis. This special relationship has evolved in an interesting way to help coral to survive changes in water temperatures. In times of temperature or pH change the coral will cast off the algae that is no longer useful and capture algae that can better handle the new conditions. This is a great advantage to the coral with one major problem. There are no new algae to capture that will help it survive at these temperatures. All the color of the coral is derived from the algae and when it is cast off it leaves the coral stark white. This is what is meant by coral bleaching. Since the algae consists of about 90 percent of the energy that the coral needs to survive it only becomes a matter of time until the bleached coral starves leaving only its white skeleton behind. The good news is that if water temperatures return to normal in time, the coral will capture the algae again and recover.

Bleaching Brain Coral

The reason that reefs are so important is that they provide for a very diverse ecological system. They provide protection for fish especially when they are juvenile and have no defenses. Some fish eat the coral itself while others consume the algae. The fish are in turn eaten by larger fish or sharks and rays. Even sea birds require these reefs to produce fish for them to eat. The algae itself even helps to produce oxygen from CO2 so we are even losing our ability to deal with the CO2 that we have. The WWF in their Living Blue Planet Report (2015) have reported a decline of about 50 percent in the populations of fish that humans utilize and reefs have been hit just as hard in the last 30 years.

But what can we do? This is a monstrous problem that cannot be solved by any one person but know that every little bit can help. We can only stop the bleaching by reducing CO2 and that means reducing our reliance on coal and gas power. Support renewable energy sources and nuclear power. Reduce the amount of electricity that you use in your home. Drive less, regardless of if you have an electric car or not. It does not do much good for you to have an electric car only to charge it from a coal power plant. Eat seafood from sustainable sources and when on vacation use sunblock that is reef safe. Avoid using plastic and if you do, recycle it. I’m positive that there are many other ways that we can make a difference and I invite everyone to add comments with additional ways that we can help.


Slezak, Michael. (2016). The Great Barrier Reef: a catastrophe laid bare. Retrieved from

WWF. (2015). Living Blue Planet Report. Retrieved from